Til 1C NAUTILUS. 113 



Segment ina armigern Say. 1. 2. Common. 



Physa heterostropha Say. 1, 2, 3. Common. 



Aplexa Itypnoruin Linne. 2. Common. 



Campeloma decisum Say. 1. Apparently not common. 



My thanks are due to Dr. V. Sterki tor determining the Pisidia. 



JOHN H. THOMSON, PH. D. 



The subject of this memoir was born in Westport in 1824, and died 

 in the city of New Bedford, Mass, (but a few miles from his birth- 

 place), July, 1896, aged 71. He had the usual public school and 

 academic education of the time. In early life, like so many New 

 England coast town boys, he took to the sea, and soon reached the 

 post of master. He spent some years in California and South Amer- 

 ica, and returning to New Bedford, he settled there for life. He 

 developed an early fondness for natural history, and in this, finally 

 narrowed down to the science of conchology. He at once became 

 fascinated with the subject, and spared no time, pains, or money in 

 his enthusiastic determination to master his subject. He was fortu- 

 nate at this juncture to fall into the hands of so capable and sympa- 

 thetic an instructor as Dr. Augustus A. Gould, to whom he ever felt 

 grateful for giving him a fuller and clearer insight into the delicate 

 minutiae, so essential in describing many species and varieties of 

 shells. By this association he was greatly aided and stimulated in 

 his subsequent pursuit and study. He soon became known as a most 

 conscientious and reliable student of conchology, and soon made many 

 friends ; his correspondents were among the most noted of his time, 

 in both hemispheres. He obtained and carefully studied the works 

 of the leading conchological authorities, without regard to price, al- 

 though he was never a rich man. 



As a collector, his success in securing species from remote parts 

 was really phenomenal. He sold his earliest and largest collection, 

 during the Franco-Prussian war, to an institution, I think, in Bel- 

 gium, but through the misfortunes of war it was in some manner con- 

 fiscated, and so the purchaser lost his prize. His later and last col- 

 lection is owned by the writer of this article. Among the many 

 societies of which Dr. Thomson was a member, two stand pre- 

 eminently conspicuous, The Zoological Society of London and the 

 Academy of Natural Sciences of Philadelphia. I am credibly in- 



